For North Melbourne to seriously challenge the competition's best teams this season it needs to bring its A-game every week, vice-captain Jack Ziebell says.

At their best in 2014, the Roos have looked the top-four contender that some commentators predicted, with their wins over Port Adelaide, the Sydney Swans at the SCG and Fremantle at Patersons Stadium outstanding.

But after beating the Swans in Sydney for the first time in 10 years in round four, North was smashed by Collingwood six days later. Along with an equally uninspiring loss to Essendon in round one, it raised the question: is North a contender or a pretender?

Ziebell spoke with AFL.com.au on Monday at Arden Street, where the mood among the North players was buoyant after their 13-point win over the Dockers.

The vice-captain said beating Freo in Perth for the first time in seven years had been fantastic for North's self-belief, but acknowledged the Roos still had "a lot to prove".

"If you don't bring your A-game, anyone can beat you and that's happened to us a couple of times this year," Ziebell said.

"Obviously you go out there and try to win games every week, but sometimes you don't put it all together that well and that's the frustrating part about football.

"But the good sides can put it together every week, so that's our major role now: to try and figure out how we can put it together week in, week out for the rest of the year.

"If we can do that, we'll be a hard side to play against."

After six rounds, North sits fifth on the ladder with a 4-2 record.

It has done so without its skipper Andrew Swallow, who played in the VFL on Sunday to mark his first game since rupturing his left Achilles tendon last season, while Ziebell missed rounds three to five with a shoulder injury and stars Daniel Wells (foot) and Scott Thompson (suspension) missed last Friday night's game.

Ziebell said North's ability to cover for absent stars showed its growing depth, with players like Levi Greenwood and Ben Jacobs coming in to play important midfield roles and key defender Joel Tippett helping to cover Thompson's absence against Freo.

"The depth of our side has been tested and I think it's responded really well," Ziebell said.

Ziebell expected Swallow would be pushing to return for this Sunday's clash with Gold Coast at Etihad Stadium after he had 23 disposals in about 50 per cent game for North Ballarat.

"He got through unscathed on the weekend and I think he played pretty well, so that's not bad for a bloke who's had nine months off," Ziebell said.

"He'll just start to get really hungry now to get back in the senior side and I think he'll be pushing the coaches this week.

"But we'll see how he goes. Hopefully he'll play sooner rather than later."